WASHINGTON — Before the 2010 midterm elections, speculation was rampant that if the Republicans took over the House, they would kill the fledgling, an independent body that investigates complaints of misbehavior.

John A. Boehner, who is now House speaker, and other Republican leaders had vigorously opposed the creation of the office, which was the brainchild of Mr. Boehner’s predecessor, Speaker Nancy Pelosi, in 2008. Anticipating its demise, Leo Wise, the office staff director and chief counsel, announced in October that he was leaving for a job with the United States attorney’s office for the District of Maryland.

But since assuming control, House Republicans have left the office largely intact, much to the surprise of lawmakers in both parties. Omar Ashmawy, the new staff director and chief counsel, said the office would continue to pursue complaints as aggressively as it did under Mr. Wise.

Good-government groups are taking a it-and-see attitude on whether the office will be as persistent in going after Republicans now as it was in investigating Democrats when they were in the majority.

“The question is how is the Republican leadership going to react when the O.C.E. starts going after its people,” said Norman J. Ornstein, an ethics expert at the American Enterprise Institute who lobbied for the creation of the office.

In an e-mail, Michael Steel, a spokesman for Mr. Boehner, said the speaker had no plans to change the office’s mandate or mission. Mr. Steel also said its financing would not be cut. Mr. Ashmawy, who was appointed staff director on Friday after serving as acting director, said he did not feel the need to modify office operations. Several lawmakers have criticized the office for overreaching in its investigations.

“Despite the controversies about the status of the office, in the 112th Congress we are going to do the mission we were asked to do before,” he said. “There will be no change.” Controversial cases are nothing new for Mr. Ashmawy, who joined the ethics office in 2009 as an investigator. As a former senior judge advocate general for the Air Force, he helped successfully try the case against Salim Ahmed Hamdan, a driver for Osama bin Laden, before the first United States war crimes tribunal since World War II.

In 2007, Mr. Ashmawy won national attention when he defended a young airman, Cassandra Hernandez, who said she was gang-raped at a party but was herself charged with committing indecent acts with the men she said had attacked her. Those charges were dropped. Mr. Ashmawy will be working for the ethics office’s original board, although the two top board members have switched jobs. The board, largely made up of former members of Congress, is appointed by the House speaker and the minority leader. Porter J. Goss, a Republican who represented Florida in the House and is a former director of the Central Intelligence Agency, will take over as chairman. The co-chairman will be another former congressman, David E. Skaggs, a Democrat from Colorado. Mr. Skaggs served as the board’s chairman for the past two years under the Democratic majority.

The office has repeatedly clashed with the House Committee on Standards and Official Conduct, commonly known as the ethics committee. The office looks into cases against members of Congress and refers them to the ethics committee for further investigation. The committee has been accused of being soft on members of Congress, while some lawmakers have complained that the ethics office has been overly aggressive and inconsistent in deciding which allegations to pursue and which to ignore.

No one has been more critical of the ethics office than the Congressional Black Caucus. At least eight black lawmakers have been the focus of its investigations, Repesentatives Charles B. Rangel, of New York and Maxine Waters of California, both Democrats. One member of the black caucus, Representative Marcia L. Fudge, Democrat of Ohio, introduced a bill that critics said would have crippled the office. The legislation, which died when the previous Congressional session ended, would have prevented the ethics committee from issuing public statements in cases in which the ethics office had recommended that a complaint be dismissed. The existing rule gives the ethics committee discretion to release information in such situations.

The measure also would have prevented the ethics office from looking into any matter except on the basis of “a sworn complaint from a citizen asserting personal knowledge of any alleged violation.” Currently, a preliminary review can be started if two board members, one from each party, ask for it. Representative Emanuel Cleaver II, a Democrat from Missouri who is the new chairman of the black caucus, said it continued to have issues with the ethics office.

“We want to ensure justice and fairness,” he said. Mr. Cleaver and other caucus members did not respond to questions about what specific changes they would propose. Mr. Ashmawy said he had not tried to talk to caucus members; nor, he added, had they reached out to him. “We are very concerned about effects of an investigation on members’ reputations,” he said.